首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   525篇
  免费   20篇
  国内免费   5篇
耳鼻咽喉   9篇
儿科学   22篇
妇产科学   15篇
基础医学   69篇
口腔科学   18篇
临床医学   59篇
内科学   73篇
皮肤病学   13篇
神经病学   15篇
特种医学   25篇
外科学   102篇
综合类   31篇
预防医学   42篇
眼科学   5篇
药学   26篇
中国医学   6篇
肿瘤学   20篇
  2022年   10篇
  2021年   18篇
  2020年   11篇
  2019年   5篇
  2018年   9篇
  2017年   7篇
  2016年   5篇
  2015年   12篇
  2014年   21篇
  2013年   23篇
  2012年   28篇
  2011年   18篇
  2010年   24篇
  2009年   14篇
  2008年   24篇
  2007年   28篇
  2006年   33篇
  2005年   23篇
  2004年   20篇
  2003年   15篇
  2002年   13篇
  2001年   14篇
  2000年   11篇
  1999年   8篇
  1998年   9篇
  1997年   12篇
  1996年   13篇
  1995年   10篇
  1994年   7篇
  1993年   7篇
  1992年   5篇
  1991年   7篇
  1990年   3篇
  1989年   6篇
  1988年   5篇
  1987年   4篇
  1985年   9篇
  1984年   7篇
  1983年   2篇
  1982年   7篇
  1981年   2篇
  1980年   2篇
  1978年   4篇
  1977年   4篇
  1976年   4篇
  1975年   5篇
  1974年   4篇
  1973年   3篇
  1971年   2篇
  1968年   3篇
排序方式: 共有550条查询结果,搜索用时 15 毫秒
1.
The purpose of this study was to verify the arthroscopic meniscus repair by second-look arthroscopy. From November 2001 to October 2005, 28 meniscus (18 medial and 10 lateral) were repaired in 26 patients (two patients had both menisci in one knee repaired). There were 11 females and 15 males. The average age at surgery was 25.5 (range, 13 to 52 years of age). The indication for repair was a full-thickness, vertical tear > or = 8 mm. Meniscus repair was combined with partial meniscectomy of posterior horn because of horizontal tear in 3 cases. In 1 zone 14 meniscus were injured and in 2 zone--also 14 meniscus, according to Cooper's classification. All patients had anterior cruciate ligament rupture. The average time interval between the injury and the repair was 22 weeks (range, 2 weeks to 2 years). The inside-out suture was used in 18 repairs, all inside--3 repairs, outside-in--2 repairs and a mixed technique--5 repairs. Arthroscopic evaluation of meniscus repair was performed on average after 15 weeks (range, 2 months to 37 weeks) since the suture. That was done during the second stage of treatment--ACL reconstruction. There were 78.6% of completely healed repairs, 10.7% of incompletely healed and 10.7% were not healed.  相似文献   
2.
3.
For the 1983 nesting season, Forster's tern (Sterna forsteri) reproductive success was significantly impaired on organochlorine contaminated Green Bay, Lake Michigan compared to a relatively uncontaminated inland location at Lake Poygan, Wisconsin. Compared with tern eggs from Lake Poygan, eggs from Green Bay had significantly higher median concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), other polychlorinated dibenzo-p-dioxins (PCDDs), total polychlorinated biphenyls (PCBs), total (three congeners) non-ortho, ortho' PCBs, five individual PCB congeners known to induce aryl hydrocarbon hydroxylase (AHH) and several other organochlorine contaminants. Conversions of analytical concentrations of TCDD and PCB congeners based on relative AHH induction potencies allowed for estimation of total 2,3,7,8-TCDD equivalents. Two PCB congeners, 2,3,3,4,4- and 3,3,4,4,5-pentachlorobiphenyl (PeCB) accounted for more than 90% of the median estimated TCDD equivalents at both Green Bay and Lake Poygan. The median estimated TCDD equivalents were almost 11-fold higher in tern eggs from Green Bay than in eggs from Lake Poygan (2175 and 201 pg/g). The hatching success of Green Bay sibling eggs from nests where eggs were collected for contaminant analyses was 75% lower at Green Bay than at Lake Poygan. Hatchability of eggs taken from other nests and artificially incubated was about 50% lower for Green Bay than for Lake Poygan. Among hatchlings from laboratory incubation, those from Green Bay weighed approximately 20% less and had a mean liver weight to body weight ratio 26% greater than those from Lake Poygan. In both field and laboratory, mean minimum incubation periods were significantly longer for eggs from Green Bay compared to Lake Poygan (8.25 and 4.58 days, respectively). Mean minimum incubation time for Green Bay eggs in the field was 4.37 days longer than in the laboratory. Hatchability was greatly improved when Green Bay eggs were incubated by Lake Poygan adults in an egg-exchange experiment, but was sharply decreased in Lake Poygan eggs incubated in Green Bay nests. Nest abandonment and egg disappearance were substantial at Green Bay but nil at Lake Poygan. Thus, not only factors intrinsic to the egg, but also extrinsic factors (parental attentiveness), impaired reproductive outcome at Green Bay. The epidemiological evidence from this study strongly suggested that contaminants were a causal factor. AHH-active PCB congeners (intrinsic effects) and PCBs in general (extrinsic effects) appeared to be the only contaminants at the concentrations measured in eggs, capable of producing the effects that were observed at Green Bay.  相似文献   
4.
The cytotoxicities of free cyanoacrylic nanoparticles, free Adriamycin, Adriamycin-loaded nanoparticles and a mixture of Adriamycin and nanoparticles are compared in cancer cell cultures. Increased cytotoxicity was observed in the sensitive (DC3F) subline when Adriamycin was in particulate form rather than free. In the derived pleiotropic resistant subline (DC3F AD/AZA), sensitivity to Adriamycin was completely restored with the conjugate. Addition of verapamil or amiodarone allowed an enhancement of efficiency of tenfold for free Adriamycin and between two- and fourfold for its conjugate form. Vectorization by nanoparticles and pharmacological modulation of cell membrane can act in synergy in synergy to overcome the resistance to Adriamycin in vitro.  相似文献   
5.
Subsurface soil from a National Priorities List landfill containing about 2.5% polychlorinated biphenyls (PCBs) was extracted and the extract cleaned by Florisil® slurry and alumina column chromatography. The refined extract contained 48 mg/mL PCB, mainly trichlorobiphenyls and tetrachlorobiphenyls, traces of polychlorinated naphthalenes, 125 g/mL 2,2-bis-p-chlorophenyl-1, 1-dichloroethylene (DDE), and low levels of chlorinated dibenzofurans. The refined extract was dissolved in corn oil and administered intraperitoneally to weanling (day 20) female rats on days 20 and 21; rats were terminated on day 22. Limited data indicated possible hematopoietic effects, including neutrophilia. There were no changes in relative uterus, kidney, or adrenal gland weights between total doses of 3 to 96 mg/kg total PCB. Relative liver weights increased significantly at 36 mg/kg and activities of P450s 1A1 (as ethoxyresorufin O-dealkylase) and 2B (as pentoxyresorufin O-dealkylase) increased at 12 mg/kg and plateaued at 36 (P450 1A1) or 48 (P450 2B) mg/kg. Serum total thyroxine (T4) declined significantly at doses of 36 mg/kg and greater; thyroid follicular epithelial cells were significantly larger within the same dose range, but the follicular colloid area decreased to less than 60% control values at 12 mg/kg and remained at this size through 72 mg/kg. Maximum mobilization of T4 apparently occurred at 12 mg/kg and attenuated measured declines in circulating levels. Even though a large proportion of proven and probable estrogenic chlorobiphenyls (CBs) were present, the lower amounts of more potent antiestrogenic aryl hydrocarbon (Ah) receptor agonists and/or decreased responsiveness because of low serum T4 levels may have antagonized the uterotropic response.  相似文献   
6.
Lake Szmaragdowe and Czarnog?owy Reservoir are both characterized by atypical origin as both were formed when quarries were flooded. The geological substrates of the two basins are unique, and they are both highly valued as recreational and tourist destinations. These two basins are among the most interesting in northwestern Poland. Studies of their thermal regimes confirmed that water mass mixing in Lake Szmaragdowe is bradymictic. The waters in the Czarnog?owy Reservoir mix entirely to a depth of 20 m, and this layer is also characterized by bradymixia. Deeper waters do not mix. This indicates that mixing in this basin is of the meromictic type.  相似文献   
7.
ObjectiveTo ascertain antimicrobial susceptibility profile of Proteus mirabilis (P. mirabilis) from clinical urine specimens at a university hospital in the spate of its recorded increasing resistance patterns.MethodsThe study was retrospective in nature. Data generated from urine cultures of patients at University of Calabar Teaching Hospital for a period of five years (2004–2009) were compiled. Relevant information obtained were age and gender of patients, organisms recovered and their antibiotic susceptibility patterns. P. mirabilis was identified using standard laboratory procedures.ResultsP. mirabilis showed the highest resistance against ampicillin, cloxacillin, amoxicillin, tetracycline, co-trimoxazole, erythromycin and chloramphenicol (100%–37.2%) while colistin, ofloxacin, ciprofloxacin, ceftriaxone, nalidixic acid and nitrofurantoin recorded the highest activity (59.1%–96.9%) with no drug recording 100% activity. The resistance of the nosocomial isolates of the organism were significantly higher than the community acquired isolates against that of the common antibiotics in use (P<0.05).ConclusionsExtreme caution should be exercised in antibiotic administration in hospital setting and the potential benefits adequately assessed while control of nosocomial infections be given a priority so as to limit the spread of resistant bacteria.  相似文献   
8.
9.
10.
Proposed at the beginning of the twentieth century to explain the origin of eukaryotic organelles from prokaryotes, endosymbiosis is now medically defined by various interaction patterns between microorganisms and their residing hosts, best exemplified by the bacterial endosymbiont Wolbachia identified in arthropods and filarial nematodes, which can influence normal development, reproduction, survival and transmission of the hosts. Based on the transmission modes, vertical or horizontal, and the function of the endosymbionts, the host–symbiont dependence can be divided into primary or secondary. In dermatology, the role of endosymbionts in skin ectoparasitosis has aroused great interests in the past years. Riesia pediculicola is a primary bacterial endosymbiont in body lice Pediculus humanus, and supplement their hosts with vitamin B, especially pantothenic acid. In cimicosis, the Gram‐negative Wolbachia can synthesize biotin and riboflavin, which are crucial for the growth and reproduction of the bedbug Cimex lectularius. In human demodicosis and rosacea, further study is required to prove the pathogenic role of the Gram‐negative bacteria Bacillus oleronius or the Gram‐positive bacteria Bacillus cereus demonstrated in the Demodex mites. The high infection rate of adult female ticks Ixodes ricinus with the Gram‐negative bacteria Midichloria mitochondrii present in the mitochondria in diverse ovarian cells, with the high seroprevalence rate in tick‐exposed subjects, raises the possibility that this non‐pathogenic endosymbiont may play a role in immune response and successful transmission of the tick‐borne pathogen. The anaerobic protozoan Trichomonas vaginalis and bacteria Mycoplasma hominis are two obligate parasites in the urogenital epithelium, with partially overlapping symptoms. Intracellular localization of Mycoplasma hominis can avoid host immune response and penetration of antibiotics, while Trichomonas vaginalis infected with Mycoplasma hominis seems to have a higher cytopathic activity and amoeboid transformation rate. Further study on the biology and pathogenesis of different endosymbionts in dermatological parasitosis will help for the development of new treatment modalities.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号